MM API: V4L2_EVENT_RESOLUTION_CHANGE event never received

I’m using the Multimedia API on JetPack 4.2.2 and try to setup the NvVideoDecoder.
As I understood, the NvVideoDecoder can only be used (setup capture plane) after the application has dequed an V4L2_EVENT_RESOLUTION_CHANGE event. However, I never receive this event in my custom application. I studied the samples code (00_video_decode and 14_multivideo_decode) and copied the code into my own application.

  1. Create NvVideoDecoder in non-blocking mode
  2. Subscribe to V4L2_EVENT_RESOLUTION_CHANGE event
  3. Create and start device poll thread (why do I need an own thread for this?)
  4. In the main loop I call SetPollInterrupt, wait on the semaphores, and dqEvent:

    dec->SetPollInterrupt();
    decoderPollCtx.pollthread_sema);
    sem_wait(&decoderPollCtx.decoderthread_sema);
    v4l2_event ev = {};
    int ret = dec->dqEvent(ev, 100);
    if (ret == 0 && ev.type == V4L2_EVENT_RESOLUTION_CHANGE)
    {
    query_and_set_capture(&decCtx);
    }

The event is never dequed and query_and_set_capture is never called, even after several minutes and hundreds of loop iterations.
What exactly has to be done to cause the kernel to emit a V4L2_EVENT_RESOLUTION_CHANGE event?

The 00_video_decode sample interestingly works, but only the version that was installed via the SDK in /usr/src. If I download the samples as part of the Multimedia-API package (L4T 32) from the download site and build them, it can’t decode and play the sample video.

Hi,
The samples have to fit release version. We suggest you install jetson_multimedia_api packages through SDKManager and build your application by referring to header files in

/usr/src/jetson_multimedia_api/include